Conventional reciprocation switching devices for pumps typically call for, as described in Japanese Utility Model Publication No. 40805/1974 fitting a piston to the inside of the cylinder body so as to slide along the cylinder body; providing the said piston with two kinds of movable valves to control fluid pressure applied to one side of the piston and fluid pressure applied to the other side of the piston; and installing a valve operator at the center of the said piston to operate the two kinds of valves by snap-action by means of a spring working in relation to the reciprocating movement of the piston.
As a compressed coil spring is used for such a conventional device, it requires a spring fitting rod for attaching the spring; the structure that calls for so fitting this rod as to allow it to rotate around the valve operator installed at the center of the device; and a spring holder section so fitted to the said spring fitting rod as to slide against it and also to rotate around sections incorporated with the piston as one body. Therefore, such a conventional device presents a problem in that the assembling of those parts as described above is difficult and complicated and that the reduction of the cost is limited due to the numerous parts required.
Further, a known example of a conventional reciprocation switching device for a diaphragm pump is described in Japanese Patent Publication No. 23303/1967.
A device under the said patent consists of, as shown in FIG. 16, switching mechanism section 512 provided inside switching device body 511; working rod 515 inserted through said switching mechanism section 512 and reciprocated by working fluid supplied to and exhausted from two working fluid chamber 513 and 514 by turns; switching operator 519 so fitted between the larger diameter section 516 of said working rod 515 and sleeve 517 as to be able to move and be moved to a side or to the other side of switching valve chest 518; cavity-shaped switch 521 that is switched by said switching operator 519 and switches supply and exhaust to and from two working fluid chambers 513 and 514 of working fluid supplied to switching valve chest 518; and spring 522 to hold switching operator 519 at one side or the other side of switching valve chest 518 by applying spring pressure perpendicular at the neutral point to said switching operator 519.
Such conventional devices further call for moving switching operator 519 by means of reciprocating movements of working rod 515; sliding switch 521 by said switching operator 519; controlling supply and exhaust of working fluid (the air) from and to the two working fluid chambers (air chambers) 513 and 514; and continuously reciprocating working rod 515.
Diaphragms 523 and 524 are a part of both ends of said working rod 515. These diaphragms 523 and 524 partition the chambers to form said working fluid chambers 513 and 514 and pump chambers 525 and 526. As said working rod 515 moves, volumes of said pump chambers 525 and 526 change, thus creating pumping strokes. For example, in case working rod 515 moves towards the right, the liquid contained in chamber 525 at one side of the device is pushed, by volume contraction of said pump chamber 525, out of discharge port 528 through check valve 527 at the discharging side. Meanwhile, the liquid is sucked, by volume augmentation of pump chamber 526 at the other side, out of suction port 529 into said pump chamber 526 through check valve 530 provided at the suction side. Such right and left pumping action is repeated by turns by the automatic switching of working fluid at said switching mechanism section 512.
In such conventional reciprocation switching devices, the configuration for the spring to apply pushing pressure to switching operator 519 calls for attaching cylindrical slider 531 to one end of compressed coil spring 522; insetting one ball-shaped end 534 of activator 533 in cavity 532 at the end of said slider 531, so as to allow ball-shaped end 534 to rotate; and insetting the other ball-shaped end 535 of activator 533 in cavity 536 of said switching operator 519 so as to allow it to rotate.
Thus, compressed coil spring 522 is used in a conventional structure, and therefore it is necessary to install said cylindrical slider 531 and activator 533 between said spring 522 and switching operator 519, a configuration which presents a problem in that the assembling of such parts is not an easy task.
Such a conventional configuration further presents a problem in that, as cavity-shaped switch 521 slides along the working rod, abrasion tends to occur between said switch 521 and the opposing metal and that it thus becomes necessary to use special wear-resistant metal at such sliding section.
The objective of the present invention is, by using a spring of a special shape for the snap action of the reciprocation switching device for a pump, to make it possible to install such spring of a special shape directly in the valve operator or the switching operator so that number of parts can be reduced; configuration becomes easier; and the cost of the device can be largely reduced compared with conventional devices.
Another objective of the present invention is to improve durability of the valve configuration without using special metals.
A further objective of the present invention is to make it considerably easier to attach the spring used for the snap action of a reciprocation switching device for a pump.
A further objective of the present invention is to make the diameter of such reciprocation switch device smaller.
The present invention relates to a reciprocation switching device for a pump in which piston 21 is so fitted into cylinder body 11 as to be able to slide therein; two kinds of valves 27 and 31 that control pressure of working fluid applied to one side and to the other side of piston 21 are attached to said piston 21 so as to be allowed to move freely; and valve operator 46 that operates said two kinds of valves 27 and 31 by the snap action of spring related to reciprocating movement of the piston is provided at the center of said piston 21, and the present invention calls for symmetrically providing each of C-shaped wire springs 43, which serve as the aforementioned spring, between spring fitting section 41, which forms a part of piston 21, and said valve operator 46 at the center of the piston.
Further, according to the present invention, when valve operator 46 is moved in relation to movement of piston 21, from the starting of movement of valve operator 46 to the neutral point, where wire springs 43 become perpendicular to the direction of piston rod, compressive force is applied to C-shaped wire springs 43 in a direction so as to push the edge of the spring towards the other side so that the wire spring is flexed; and after the said neutral point, valve operator 46 is immediately switched to the reversed stable position by restoring force of same wire springs 43 and held at such stable position.
According to the present invention, it is possible to considerably reduce the number of parts compared with conventional device using pressure coil springs and also to make installation of such wire spring much easier, and thus product cost can be lowered on a large scale.
The present invention further calls for a reciprocation switching device including switching valve chest 122 provided in the body of switching device 111; working rod 113 inserted through said switching valve chest 122 and reciprocated by working fluid supplied and exhausted by turns into and from two working fluid chambers 118 and 119; switching operator 123 movable and fitted around said working rod 113 in the direction of the rod and to be moved from one side or to the other side of switching valve chest 122; cavity-shaped switch 127 activated by said switching operator 123 to switch supply and discharge of working fluid supplied to switching valve chest 122 into and from two working fluid chambers 118 and 119; and a spring to hold switching operator 123 at one side or the other side of switching valve chest 123 by applying spring pressure to said switching operator 123, the direction of pressure at the neutral point being perpendicular to the switching operator, wherein C-shaped wire spring 164 which is formed by bending wire material with circular cross section so that the both ends face each other is used for the aforementioned spring; both ends 172 of said wire spring 164 are inserted into holes 174 horizontally bored in said switching operator 123 and movable therein; and straight portion 171 of said wire spring 164 is so fitted in spring holder 163, which is installed to face said switching valve chest 122, as to be allowed to rotate freely.
According to the present invention, as working rod 113 moves, switching operator 123 is also moved; as said switching operator 123 approaches the neutral point, wire spring 164 between switching operator 123 and spring holder 163 rotates with its straight portion 171 as the fulcrum and is simultaneously compressed; the switching operator having passed the neutral point, restoring force conserved in wire spring 164 is immediately released in the direction where the working rod is moving to; and switching operator 123 fitted around working rod 113 so as to be movable along the working rod is instantly moved, as far as its fitting allows, to its terminal point in the moving direction of the rod. At this moment, switching operator 123 is caught by switch 127, which is also moved immediately; and supply and discharge of working fluid from and into working fluid chambers 118 and 119 is switched instantly.
Assembling of the parts calls for inserting both ends of wire spring 164 into switching operator 123 and fitting spring holder 163 to the straight portion 171 of said wire spring 164. Pressurization is applied from said spring holder 163 to wire spring 164.
According to the present invention, installation of the spring in the switching valve chest is quite easy, requiring only fitting the wire spring to the switching operator and setting the spring holder, and the number of necessary parts is relatively few. Therefore, product cost can be considerably less than that of conventional devices.
The present invention further relates to a reciprocation switching device for a pump including switching mechanism section 244 provided inside switching device body 241 in order to control the switching of supply and discharge of working fluid into and from the two working fluid chambers 242 and 243 alternately; working rod 245 inserted through said switching mechanism section 244 and reciprocated by working fluid alternately supplied and discharged into and from the two working fluid chambers 242 and 243; switching operator 261 fitted around said working rod 245 so as to be movable along the working rod and moved to the switching positions at one side and the other side in relation to reciprocating movement of working rod 245; and wire springs 271 to push said switching operator 261 to the switching position at one side or the other side by applying spring pressure perpendicular to said switching operator 261 at the neutral point, wherein said wire springs 271 are formed into C-shape by bending both ends of wire material so that the both ends face with each other; both ends 272 of each of said wire springs 271 are so inserted into holes 273, which are horizontally bored in said switching operator 261 or material 266 that forms a part of the switching operator 261, as to be allowed to rotate therein; and straight portion 274 of each of said wire springs 271 is so fitted in spring holder 275 provided in said switching device body 241 as to be allowed to rotate. The device further includes valves 291, 292 and 294, which are provided in said switching operator 261 and switched by said switching operator 261 to switch supply and discharge of working fluid supplied into switching mechanism section 244 into and from the two working fluid chambers 242 and 243 by contact with and separated from valve seats 285, 286, 288 and 289.
According to the present invention, as working rod 245 moves, switching operator 261 is also moved; as said switching operator 261 approaches the neutral point, wire springs 271 between switching operator 261 and spring holders 275 rotate with their respective straight portion 274 as the fulcrum and are simultaneously compressed; switching operator 261 having passed the neutral point, restoring force conserved in wire springs 271 is immediately released in the direction where the working rod is moving to; and switching operator 261, which is so fitted around working rod 245 as to be movable in its axial direction, is in an instant moved, as far as the fitting allows, to the terminal point in the direction of the working rod's movement. With this movement of switching operator 261, valves 291, 292 and 294 are instantly moved; and supply and discharge of working fluid into and from working fluid chambers 242 and 243 is also switched immediately.
Assembling of the parts calls for fitting straight portions 274 of wire springs 271 to spring holders 275 and inserting both ends 272 of each wire spring 271 into switching operator 261.
The present invention has a benefit in that the number of parts required can be reduced and that installation of the spring is much easier, so that a large scale reduction in cost is possible. Furthermore, because supply and discharge of working fluid is switched by means of contact with and separation of valves from valve seats, no part of the valve structure is exposed to abrasion, so that deterioration of durability due to abrasion can be prevented.
The present invention further relates to a reciprocation switching device for a pump wherein piston 321 is fitted into cylinder body 311 so as to be allowed to slide freely; cylinder body 311 incorporates at its upper part as one body valve seat attaching section 314; two kinds of valves 327 and 331 are so attached to be allowed to move and oppose two kinds of valve seats attached to said valve seat attaching section 314, said valves to serve to control, in relation to pressure of working fluid applied to the lower side of piston 321, pressure of working fluid applied to the upper side; valve operator 346 to operate two kinds of valves 327 and 331 by means of snapping action of springs in relation to reciprocating movement of piston 321 is attached to the center of said valve seat attaching section 314; and C-shaped wire springs 343 are attached, serving as the aforementioned spring, between spring attaching section 341, which forms a part of said valve seat attaching section 314, and said valve operator 346 at the center.
According to the present invention, valve operator 346 is moved in relation to the movement of piston 321, wherein, from the starting of valve operator 346's movement to the neutral point where wire springs 343 become perpendicular to the direction of the piston, compressive force is applied to C-shaped wire springs 343 in the direction of pushing the edges of the springs, which have a gap in between them, so that the springs yield, and the springs having passed the neutral point, valve operator 346 is instantly switched to the stable condition at the opposite side by restoring force of said wire springs 343 and held in such condition.
The present invention has the benefit in that the number of parts required can be considerably reduced from that required for a conventional device using a compressed coil spring and that installation of the spring is quite easy, so that a large scale reduction of product cost is possible. Furthermore, because valve seats and valves are installed by means of the valve seat attaching section at the upper part of the cylinder body, it is possible to make the diameter of the piston and the cylinder smaller.
The present invention further relates to a reciprocation switching device for a pump wherein piston 412 incorporated with pump operation rod 413 at its lower part as one body is so fitted inside cylinder body 411 to be allowed to slide; valve body 431 at the upper part of cylinder body 411 forms a part of the cylinder body; working fluid intake vents 435 to supply working fluid, which has been conveyed into the lower part of piston 412, also to the upper side of piston 412 and working fluid exhaust vents 446 to discharge working fluid at the upper part of piston 412 are provided on said valve body 431; intake valve 433 is so provided at the upper end of working fluid intake vents 435 as to open and close freely; valve operators 453 and 455 to open or close intake valve 433 and exhaust valve 443 respectively in relation to reciprocating movement of piston 412 are so provided at the center of said valve body 431 as to be able to move up and down; C-shaped wire springs 452 in order to operate, by means of snapping action, said valve operators are provided between spring attaching sections 441, which project downward from said valve body 431, and valve operator 453; and wherein working fluid supplier 425, into which working fluid to be supplied to the lower part of piston 412 is constantly conveyed, is provided on the upper side of said valve body 431 concentric to each other; said intake valve 433 is provided between said working fluid supplier 425 and working fluid intake vents 435 of valve body 431; and working fluid exhaust ducts 447 and 449, including said working fluid exhaust vents 446, on the outer side of valve body 431.
According to the present invention, while valve operators 453 and 455 are held up by wire springs 452, working fluid exhaust vents 446 are kept closed by exhaust valve 443 and intake valve 433 is kept open by working fluid intake vent 435. Therefore, working fluid, which is constantly supplied to working fluid supplier 425, is applied with pressure through working fluid intake vents 435 into the space above piston 412, thus pushing down piston 412. When said piston 412 reaches the point immediately before the lowest limit, valve operators 453 and 455 are moved downward, so that exhaust valve 443 is opened together with closure of intake valve 433; and piston 412 is moved upward by air supplied to its lower area.
The present invention has the benefit in that passage for supply of working fluid can be compactly provided in the center of the valve body and that it becomes possible to make the diameter of reciprocation switching device of this kind smaller.